The 36-year-old actress has been spotted with a baby bump on numerous occasions but never came out to confirm it. She also said that she plans to take time off after finishing her new movie "Devil's Knot" with Colin Firth, reported Aceshowbiz.
"Frankly, I'm feeling very round. I'm always feeling like I'd like to eat everything in sight. I'm going to take a little time off - and go have a baby," Witherspoon said on the red carpet of the Renaissance Award in a ceremony at The Ritz-Carlton.
"'Devil's Knot' is a very American story that revolves around "a crime that occurred in 1993 in Arkansas," she added.
Showing off her baby bump in a blue Vanessa Bruno dress, she accepted the prize from Academy Award winner Alexander Payne, who directed her in 1999's critically acclaimed "Election".
Witherspoon is married to Hollywood talent agent Jim Toth, who she married in March 2011 and the upcoming baby will be their first child together.
She was previously married to actor Ryan Phillippe, with whom she has two kids, 12-year-old daughter Ava and 8-year-old son Deacon.